What is the recommended supportive care for patients with influenza, including those with underlying respiratory conditions such as asthma or chronic obstructive pulmonary disease (COPD)?

Recommended Supportive Care for Influenza

Patients with uncomplicated influenza should maintain adequate hydration, rest at home, use antipyretics for fever control, and monitor for warning signs requiring medical attention, while those with underlying asthma or COPD require oxygen therapy targeting SpO₂ ≥92%, short-acting bronchodilators, and close monitoring of respiratory status at least twice daily. 1, 2

General Supportive Measures for Uncomplicated Influenza

Hydration and Rest

• Patients should drink plenty of fluids to maintain hydration and get adequate rest, staying home until fever-free for 24 hours without antipyretics to prevent transmission. 2
• Practice strict respiratory hygiene including covering coughs and sneezes, with hand hygiene after contact with respiratory secretions. 2

Fever Management

• Monitor temperature regularly and use antipyretics as needed for comfort. 2
• Fever typically peaks within 24 hours of onset and lasts 3 days (range 1-5 days), often reaching 38-40°C. 3

Warning Signs Requiring Immediate Medical Evaluation

• Difficulty breathing or shortness of breath 2
• Persistent chest pain or pressure 2
• Confusion or altered mental status 2
• Respiratory rate >30/min, blood pressure <90/60 mmHg, hemoptysis, or bilateral chest signs suggesting pneumonia 1

Enhanced Supportive Care for Patients with Asthma or COPD

Bronchodilator Therapy

• Initiate short-acting inhaled β2-agonists immediately, with or without short-acting anticholinergics as first-line treatment. 1
• Use nebulizers if the patient is too breathless to use standard inhalers effectively, or use spacer devices with metered-dose inhalers. 1

Oxygen Management

• Administer appropriate oxygen therapy to maintain PaO₂ >8 kPa and SpO₂ ≥92% in most patients. 3, 1
• For COPD patients with known CO₂ retention, target SpO₂ ≥90% and guide therapy by repeated arterial blood gas measurements. 3, 1
• High concentrations of oxygen can safely be given in uncomplicated pneumonia without pre-existing COPD. 3
• Obtain arterial blood gases if SpO₂ <92% or if the patient has features of severe illness. 1

Systemic Corticosteroids

• Administer prednisone 40 mg orally daily for 5 days to improve lung function, oxygenation, shorten recovery time, and reduce hospitalization duration in exacerbations. 1

Monitoring Strategy

• Check vital signs at least twice daily: temperature, respiratory rate, pulse, blood pressure, mental status, oxygen saturation, and inspired oxygen concentration. 3, 1
• Use an Early Warning Score system for convenient tracking. 3, 1
• In patients not progressing satisfactorily, perform full clinical reassessment and repeat chest radiograph. 3

Non-Invasive Ventilation

• Consider non-invasive ventilation (NIV) in COPD patients with acute hypercapnic respiratory failure. 1
• NIV may serve as a bridge to invasive ventilation in patients without pre-existing COPD who develop respiratory failure when level 3 beds are in high demand. 3, 1
• Ensure appropriate infection control measures are adopted at all times when using NIV. 3

Additional Supportive Interventions

Fluid and Nutritional Support

• Assess patients for volume depletion and their need for additional intravenous fluids. 3
• Provide nutritional support in severe or prolonged illness. 3

Cardiac Assessment

• Evaluate patients for cardiac complications, as ECG abnormalities are common with influenza (non-specific T wave and rhythm changes, ST segment deviation). 3

Discharge Criteria and Follow-Up

Stability Assessment

• Review patients 24 hours prior to discharge and ensure no more than one of the following unstable clinical factors is present: 3
  • Temperature >37.8°C
  • Heart rate >100/min
  • Respiratory rate >24/min
  • Systolic blood pressure <90 mmHg
  • Oxygen saturation <90%

Follow-Up Recommendations

• Arrange follow-up for all patients who suffered significant complications or worsening of underlying disease. 1
• Consider repeat chest radiograph if respiratory symptoms or signs persist, especially in smokers and those over 50 years of age. 3
• Further investigations including CT thoracic scan and bronchoscopy should be considered if chest x-ray remains abnormal at follow-up. 3

Critical Pitfall: Zanamivir in Airways Disease

Zanamivir (inhaled neuraminidase inhibitor) is NOT recommended for patients with underlying airways disease such as asthma or COPD due to serious cases of bronchospasm, including fatalities. 4 If antiviral therapy is indicated, oseltamivir (oral neuraminidase inhibitor) is the preferred agent for patients with underlying airways disease. 1, 2